Selective stiffening catheter
A controllable stiffness catheter comprising a shaft comprising an inner sheath defining an access lumen, an outer sheath surrounding the inner sheath and defining an annulus therebetween, the annulus having a vacuum connection at which a vacuum is applied to the annulus, and a mechanical stiffener disposed at least at a portion of the annulus.
1. A controllable stiffness catheter, comprising:
a shaft comprising:
a handle;
an inner sheath having a proximal end connected to the handle, a distal end and defining an access lumen;
an outer sheath surrounding the inner sheath to the distal end and defining an annulus therebetween, the annulus comprising a proximal portion connected to the handle and having a vacuum connection at which a vacuum is applied to the annulus;
a mechanical stiffener disposed at least at a longitudinal portion of the annulus, the inner and outer sheaths and the mechanical stiffener being sized to have at least the longitudinal portion sized for neurological vascular procedures, the outer sheath having a substantially constant outer diameter over the longitudinal portion of the annulus to the distal end, the inner and outer sheaths being longitudinally fixed with respect to one another; and
a vacuum device fluidically connected to the vacuum connection and configured to apply the vacuum to the annulus and, responsive to the vacuum being applied to the vacuum connection:
pressure is lowered within the annulus;
the outer sheath contacts the mechanical stiffener; and
the shaft is stiffened at least at the longitudinal portion at which the mechanical stiffener is disposed to substantially and passively maintain a current shape of the shaft at least at the longitudinal portion.
2. The catheter according to claim 1 , wherein, responsive to the vacuum being applied to the annulus through the vacuum connection, the longitudinal portion substantially maintains the current shape and a current orientation of the shaft at least at the longitudinal portion.
3. The catheter according to claim 1 , wherein, responsive to the longitudinal portion being disposed within neurological vasculature and the vacuum being applied to the annulus through the vacuum connection, the shaft is stiffened at least at the longitudinal portion at which the mechanical stiffener is disposed to substantially maintain the current shape and a current orientation of the shaft in the neurological vasculature.
4. The catheter according to claim 1 , wherein the mechanical stiffener allows fluid between the inner sheath and the outer sheath to move about the mechanical stiffener.
5. The catheter according to claim 1 , wherein the mechanical stiffener is disposed outside the inner sheath.
6. The catheter according to claim 1 , wherein the mechanical stiffener is disposed inside the outer sheath.
7. The catheter according to claim 1 , wherein, responsive to the vacuum being applied to the annulus through the vacuum connection, the shaft is stiffened at least at the longitudinal portion at which the mechanical stiffener is disposed without substantially straightening the shaft at the longitudinal portion.
8. The catheter according to claim 1 , wherein a magnitude of a pressure difference between an outside of the catheter and the interior of the annulus affects stiffness of the shaft such that, as the pressure difference increases, the stiffness at least at the longitudinal portion increases.
9. The catheter according to claim 1 , wherein the outer sheath comprises polyurethane and the inner sheath comprises PTFE.
10. The catheter according to claim 1 , wherein an entire length of the shaft is controllable in stiffness.
11. The catheter according to claim 1 , wherein the longitudinal portion is a distal 20 cm of the shaft.
12. The catheter according to claim 1 , wherein the mechanical stiffener is subdivided into different stiffening segments.
13. The catheter according to claim 1 , wherein the shaft has a proximal portion and the shaft further comprises a titer fitting at the proximal portion.
14. The catheter according to claim 13 , wherein:
the luer fitting provides access to the access lumen; and/or
the luer fitting fluidically connects to the vacuum connection and is configured to removably fluidically connect to the vacuum device; and/or
the luer fitting comprises first and second luer fittings, the first luer fitting providing access to the access lumen and the second luer fitting fluidically connecting to the vacuum connection and configured to removably fluidically connect to the vacuum device.
15. The catheter according to claim 1 , wherein:
the access lumen has a diameter of at least 0.4064 mm; and
the shaft has an outer diameter no greater than 1.651 mm.
16. The catheter according to claim 1 , wherein:
the outer sheath comprises a smooth inner surface; and
the mechanical stiffener is movable within the annulus with respect to the smooth inner surface of the outer sheath.
17. The catheter according to claim 1 , wherein the mechanical stiffener is at least one of granular aluminum oxide and granular silica.
18. The catheter according to claim 17 , wherein, responsive to the vacuum being applied to the annulus through the vacuum connection, the outer sheath compresses grains of the mechanical stiffener to stiffen the shaft at least at the portion at which the mechanical stiffener is disposed without straightening the shaft at the portion.
19. The catheter according to claim 1 , wherein;
the inner sheath has an outside surface;
the outer sheath has an inside surface; and
the mechanical stiffener comprises a surface roughening on at least one of the outside surface of the inner sheath and the inside surface of the outer sheath.
20. A controllable stiffness catheter, comprising:
a shaft comprising:
a handle
an inner sheath having a proximal end connected to the handle and a distal end and defining an access lumen;
an outer sheath surrounding the inner sheath to the distal end and defining an annulus therebetween, the annulus comprising a proximal portion connected to the handle and having a vacuum connection at which a vacuum is applied to the annulus;
a mechanical stiffener disposed at least at a longitudinal portion of the annulus, the inner and outer sheaths and the mechanical stiffener being sized to have at least the longitudinal portion sized for neurological vascular procedures, the outer sheath having a substantially constant outer diameter over the longitudinal portion of the annulus to the distal end, the inner and outer sheaths being longitudinally fixed with respect to one another; and
a vacuum device fluidically connected to the vacuum connection and configured to apply the vacuum to the annulus and, responsive to the vacuum being applied to the vacuum connection:
pressure is lowered within the annulus;
the outer sheath contacts the mechanical stiffener; and
the shaft is stiffened at least at the longitudinal portion at which the mechanical stiffener is disposed without substantially straightening the shaft at the longitudinal portion.